1. Field of the Invention
This invention relates to the field of post-foaming compositions, more particularly to post-foaming shaving gels, and still more particularly to a post-foaming shaving gel including (a) a surfactant system, (b) the polymers poly(ethylene oxide) and polyvinylpyrrolidone, preferably in a weight ratio falling within a specified range, and (c) a post-foaming agent.
2. Description of the Related Art
Post-foaming shaving gels, also known as xe2x80x9cself-foamingxe2x80x9d or just xe2x80x9cfoamingxe2x80x9d shaving gels, have become popular because of their unique characteristics: in use, the product is dispensed from a container in a gel form substantially free from foam, and is transformed into a foam when rubbed onto the skin. (In this respect, post-foaming shaving gels differ from xe2x80x9cshaving creamsxe2x80x9d, which are dispensed as foam.) To effect the transformation from gel to foam, a post-foaming agent comprising a hydrocarbon propellant is typically provided in the post-foaming shaving gel. The post-foaming agent volatilizes when the post-foaming shaving gel is rubbed onto the skin, thereby changing the post-foaming shaving gel into a foamy lather.
In addition to the post-foaming agent, other ingredients of known post-foaming shaving gels have included, for example, surfactants for cleaning (including soaps and synthetic detergents), gellants (also known as gelling aids) or thickeners, agents for adjusting lubricity, water, humectants, emollients, fragrances, and colorants.
As for gellants, thickeners, and agents for adding lubricity, in particular, a variety of ingredients have been mentioned in the related art. For example, U.S. Pat. No. 5,451,396 (commonly assigned to the assignee of the present application) to Villars lists as preferred gelling aids xe2x80x9cwater-soluble hydroxyalkyl cellulose or naturally derived gums such as xanthan, various synthesized polymers such as polyvinyl pyrrolidone, as well as chemical or enzymatically modified derivatives of these materials.xe2x80x9d U.S. Pat. No. 5,326,556 to Barnet, et al. refers to polyethylene oxide and hydroxyethyl cellulose as preferred water-soluble polymers. U.S. Pat. No. 5,560,859 to Hartmann. et al. discusses use of poly(ethylene oxide) as a gel stabilizer.
Several of the aforementioned compounds are found in a series of conventional shaving gels (referred to as the 14614D series) manufactured by S. C. Johnson and Son, Inc., the assignee of the present application. Each of those gels includes, among other ingredients, (a) hydroxyethyl cellulose, (b) a soap with stearic acid, palmitic acid, and triethanolamine, and (c) a post-foaming agent with either (i) isopentane and isobutane or (ii) n-pentane and isobutane, with some gels further including poly(ethylene oxide) (POLYOX(copyright) WSR 301). These gels, hereinafter, collectively will be referred to as the xe2x80x9cconventional S. C. Johnson shaving gel.xe2x80x9d
However, conventional post-foaming shaving gels, such as the conventional S. C. Johnson shaving gel, leave room for improvement in a number of respects. Consider, for example, the conventional S. C. Johnson shaving gel (with poly(ethylene oxide)). That shaving gel is an excellent shaving composition; nonetheless, a number of areas for improvement were noticed, both in manufacturing and in use. In the manufacturing process, the ingredients which comprise the shaving gel were mixed together, and the resulting, substantially liquid mixture was filled into an open, unpressurized container (such as, for example, an aerosol can), which was then pressurized and capped. To convert the substantially liquid mixture to gel form, it was necessary to let the container rest at about room temperature for about two weeks. In some cases, it was necessary to heat the container to about 130xc2x0 F. for about two to three hours to provide energy sufficient to effect the conversion to gel form. Not only was the conversion from liquid to gel form difficult, but another disadvantage was present in the manufacturing process: when the substantially liquid mixture was dispensed into the open, unpressurized container, it tended to foam rapidly if post-foaming agents having a high vapor pressure were used, or if large amounts of high or low vapor pressure post-foaming agents were used. Of course, such foaming was unacceptable because the product was intended to be a substantially foam-free gel. As a result, it was necessary to use post-foaming agents having a lower vapor pressure, or to reduce the total amount of post-foaming agents, so as to obviate the foaming problem. However, both of these solutions were disadvantageous because, when the resulting shaving gel was used, it produced a foam which was denser, heavier, and less commercially desirable than that produced by shaving gels incorporating higher-vapor pressure post-foaming agents or a greater total amount of post-foaming agents.
In addition to these manufacturing problems, a number of disadvantages arose with the conventional S. C. Johnson post-foaming shaving gel when used. For example, the characteristics of the post-foaming shaving gel were such that it was not as easy as desired to rinse the foam produced by the post-foaming shaving gel from the skin. In addition, although the post-foaming shaving gel remained in a substantially foam-free form for a number of minutes upon being dispensed, it was commercially desirable to increase this amount of time.
I believe that other commercially available post-foaming shaving gels have the same or similar disadvantages, in manufacture or use.
Accordingly, a need has arisen to overcome drawbacks associated with conventional post-foaming shaving gels, such as those discussed above, and to provide a composition, such as a post-foaming shaving gel, for example, having improved properties.
In view of the foregoing, one object of this invention is to provide a composition, such as a post-foaming shaving gel which reduces or eliminates the problem of foaming during the filling step of manufacturing.
Another object of this invention is to provide a composition, such as a post-foaming shaving gel which reduces the amount of time, heat, or energy necessary to effect a conversion from liquid to gel form during manufacturing.
Still another object of this invention is to provide a composition, such as a post-foaming shaving gel which permits use of higher vapor pressure post-foaming agents, or which permits use of a greater total amount of post-foaming agents, in comparison with conventional post-foaming shaving gels, thereby generating a more voluminous, more commercially-acceptable foam when the gel is applied to the skin.
A further object of this invention is to provide a composition, such as a post-foaming shaving gel which, when dispensed under static conditions, remains in a substantially gel-like and foam-free form for a longer period of time than conventional post-foaming shaving gels, especially when dispensed under environmental conditions of about 14 to about 50 psia and about 32xc2x0 F. to about 150xc2x0 F.
Another object of this invention is to provide a composition, such as a post-foaming, shaving gel which is easier to rinse from the skin than conventional post-foaming shaving gels.
Yet another object of this invention is to provide methods for making a composition, such as a post-foaming shaving gel having the desired properties of this invention.
A still further object of this invention is to provide a composition having the desired properties of this invention, and methods for making the same.
In view of the foregoing objects, in one aspect, this invention relates to a composition, such as a post-foaming shaving gel composition comprising about 3% to about 20% by weight of the composition of a surfactant system, about 0.05% to about 10% by weight of the composition of poly(ethylene oxide) and polyvinylpyrrolidone, in a combined amount, wherein the poly(ethylene oxide) and the polyvinylpyrrolidone are present in a weight ratio of about 1:10 to about 10:1, and about 0.1% to about 10% by weight of said composition of a post-foaming agent.
In another aspect, this invention relates to a composition comprising about 3% to about 20% by weight of the composition of a surfactant system, about 0.05% to about 10% by weight of the composition of poly(ethylene oxide) and polyvinylpyrrolidone, in a combined amount, wherein the poly(ethylene oxide) and the polyvinylpyrrolidone are present in a weight ratio of about 1:10 to about 10:1, and about 0.1% to about 10% by weight of the composition of a post-foaming agent.
In yet another aspect, this invention relates to a gel comprising about 3% to about 20% by weight of the gel of a soap, about 0.05% to about 10% by weight of the gel of poly(ethylene oxide) and polyvinyl-pyrrolidone, in a combined amount, wherein the poly(ethylene oxide) and the polyvinylpyrrolidone are present in a weight ratio of about 1:10 to about 10:1, and about 0.1% to about 10% by weight of the gel of a post-foaming agent comprising a hydrocarbon propellant.
In still another aspect, this invention relates to a composition in the form of a post-foaming gel, comprising about 3% to about 20% by weight of the composition of a water-soluble salt of a higher fatty acid, about 0.05% to about 10% by weight of the composition of (a) poly(ethylene oxide) having about 60,000 to about 120,000 linked ethylene oxide monomers and (b) polyvinylpyrrolidone, in a combined amount, wherein the poly(ethylene oxide) and the polyvinylpyrrolidone are present in a weight ratio of about 1:1 to about 1:10, and about 0.1% to about 10% by weight of the composition of a post-foaming agent comprising a hydrocarbon propellant selected from the group consisting of propane, n-pentane, isopentane, neopentane, n-butane, isobutane, and mixtures thereof, wherein the composition has a pH of about 4 to about 10.
The above-noted and other objects, advantages, and features of this invention will become more apparent from the following description of the preferred embodiments.
The preferred embodiments and the best mode for carrying out the invention will now be described.
In a preferred embodiment, this invention is a composition, such as a post-foaming shaving gel, comprising (a) a surfactant system, (b) the two polymers poly(ethylene oxide) and polyvinylpyrrolidone, within a preferred range of weight ratios, and (c) a post-foaming agent. For ease of discussion, the composition of this invention will be referred to as a xe2x80x9cpost-foaming shaving gel.xe2x80x9d However, one having ordinary skill in the art would recognize that the composition of this invention is also useful, for example, as a laundry prespotter, a drain freshener, a hard surface cleaner, or a personal cleaner such as a body wash or a hand soap.
The post-foaming shaving gel of this invention may also comprise a variety of optional ingredients, including water, humectants, emollients, colorants, and fragrances. Preferably, the pH of the post-foaming shaving gel of this invention is about 4 to about 10, more preferably about 7 to about 10, and most preferably about 8 to about 9.
In the discussion below, all percentages are by weight of the total post-foaming shaving gel composition, unless specified otherwise.
The Surfactant System
The surfactant system of the post-foaming shaving gel of my invention preferably comprises a soap, or a synthetic detergent, or one or more of either or both. The surfactant system preferably is present in an amount of about 3% to about 20% by weight of the total post-foaming shaving gel composition, and more preferably in an amount of about 16 to about 18%, and most preferably in an amount of about 17%. These ranges are preferable whether the surfactant system includes only soaps, or only synthetic detergents, or both.
The soap of the surfactant system preferably comprises a water-soluble salt of a fatty acid, most preferably a higher fatty acid. The soap of the surfactant system may be preformed. Alternatively, the soap may be formed or prepared in any conventional manner. For example, the soap may be prepared in situ by reacting a basic material such as, for example, triethanolamine (also known as xe2x80x9cTEAxe2x80x9d), sodium hydroxide, or potassium hydroxide with a higher fatty acid such as, for example, stearic, palmitic, myristic, oleic, or coconut oil fatty acid, or mixtures of these higher fatty acids. The triethanolamine soaps of stearic and palmitic acids are preferred ingredients of the surfactant system, and either one or more, and preferably both of these two soaps may be used. Preferably an excess of the basic material, such as triethanolamine, for example, is added to completely neutralize the fatty acid and to adjust the pH to the desired range.
As mentioned above, the surfactant system may comprise a synthetic detergent. I prefer that the synthetic detergent be non-ionic in character and soluble in the aqueous components of the composition. If the surfactant system comprises soap and synthetic detergent, it is preferable that the synthetic detergent be present in an amount of about 0.1% to about 8% by weight of the shaving gel composition, with the soap and synthetic detergent combined preferably totalling about 3% to about 20% by weight of the composition. Preferred synthetic detergents include water-soluble polyoxyethylene ethers of alkyl-substituted phenols, and water-soluble polyethoxylated derivatives of fatty alcohols. A particularly preferred synthetic detergent is Oleth-20, which is defined in the CTFA Cosmetic Ingredient Handbook, First Edition (1988), published by the Cosmetic, Toiletry and Fragrance Association, Inc., and incorporated herein in its entirety by reference.
Another class of preferred synthetic detergents are the water-soluble N-acyl sarcosinate salts. The N-acyl sarcosine of the N-acyl sarcosinate salt preferably is selected from those having an acyl moiety of 10 to 20 carbon atoms, and more preferably 12 to 18. The N-acyl sarcosine preferably is neutralized with a base (preferably an organic amine base, such as, e.g., triethanolamine) to produce the water-soluble salt. Preferred N-acyl sarcosines include, for example, stearoyl sarcosine, myristoyl sarcosine, oleoyl sarcosine, lauroyl sarcosine, cocoyl sarcosine, and mixtures of these sarcosines. The N-acyl sarcosine salt may be provided preformed, or may be formed in situ by neutralizing with a base as described above. The pH of the shaving gel composition preferably may be set by regulating the amount of base in this neutralization reaction.
The foregoing preferred synthetic detergents are given by way of example and not by way of limitation. Any other synthetic detergents may be employed in the surfactant system, although it is less preferable to include those which are known in the art to have an adverse effect on gel formation, such as, for example, sodium lauryl sulfate and TEA lauryl sulfate.
Overall, the surfactant system preferably comprises, and more preferably consists essentially of, a mixture of soaps of palmitic and stearic acids, preferably prepared by combining triethanolamine, palmitic acid, and stearic acid to yield triethanolamine salts of the two acids. (Alternatively, the stearic acid may be omitted to yield a soap of palmitic acid.) A weight ratio of palmitic acid to stearic acid of 1:3 to 3:1 is preferred, with a ratio of about 3:1 being even more preferred. Preferably, the soaps of the surfactant system are triethanolamine soaps. Most preferably, the palmitic acid used is that designated as xe2x80x9cpalmitic acid 93.5%xe2x80x9d, and sold by Acme-Hardesty, while the stearic acid is that sold under the trademark xe2x80x9cEmersol 132xe2x80x9d by Emery Industries.
Poly(ethylene oxide) and Polyvinylpyrrolidone
Poly(ethylene oxide), also referred to in the art as xe2x80x9cpolyoxyethylenexe2x80x9d, xe2x80x9cpoly(oxyethylene)xe2x80x9d, xe2x80x9cpolyethylene glycolxe2x80x9d, and xe2x80x9cPEGxe2x80x9d, is a linear homopolymer of ethylene oxide monomers that conforms generally to the formula H(OCH2CH2)nOH, and is non-ionic and water-soluble. Preferably, n has an average value of about 15,000 to about 120,000, more preferably about 60,000 to about 120,000, and most preferably about 90,000. xe2x80x9cPEG-90Mxe2x80x9d is the art-recognized name for the case where the average value of n is 90,000, as defined in the CTFA Cosmetic Ingredient Handbook, First Edition (1988), which is incorporated herein in its entirety by reference. The preferred grade of PEG-90M for this invention is that which is sold under the name xe2x80x9cPOLYOX(copyright) WSR 301xe2x80x9d by Union Carbide Corporation, and which has an approximate molecular weight of about four million.
Polyvinylpyrrolidone is a linear homopolymer of 1-vinyl-2-pyrrolidone monomers, and is water-soluble. Polyvinylpyrrolidone is also known as xe2x80x9cPVPxe2x80x9d, and a definition thereof is set forth in the CTFA Cosmetic Ingredient Handbook, First Edition (1988), which is incorporated herein in its entirety by reference. Preferably, the polyvinylpyrrolidone used in this invention has an average molecular weight (Mv) in Daltons of about 630,000. Most preferably, the polyvinylpyrrolidone used in this invention is that which is sold in powder form under the name xe2x80x9cPVP K-90xe2x80x9d by International Specialty Products.
I prefer that the ratio by weight of poly(ethylene oxide) to polyvinylpyrrolidone be within the range of about 1:10 to about 10:1, more preferably within the range of 1:1 to 1:10, and optimally about 9:47 (i.e., about 1:5). This is because I found that, if too much poly(ethylene oxide) was added, the gel would be undesirably elastic, while if too much polyvinylpyrrolidone was added, the gel would be undesirably stiff.
The poly(ethylene oxide) and polyvinylpyrrolidone preferably are present in an amount of about 0.05% to about 10%, totalled together, by weight of the total post-foaming shaving gel composition. Most preferably, the poly(ethylene oxide) and polyvinylpyrrolidone are present in an amount of about 0.56% (i.e., about 0.6%).
Comparative tests have shown that post-foaming shaving gels according to this invention are remarkably superior to conventional post-foaming shaving gels.
Furthermore, the post-foaming shaving gels according to this invention have made it possible to eliminate a number of ingredients used in the conventional S. C. Johnson post-foaming shaving gel, thereby simplifying and reducing the cost of manufacturing. For example, it was possible to eliminate hydroxyethyl cellulose, and it is thought that compositions according to this invention may be prepared free from such gelling aids such as alkyl glycols, polyacrylic acids, alkyl modified cellulose polymers, guar gums, xanthan gums, and mixtures thereof. Other ingredients that successfully were eliminated included lauryl alcohol and palmitamine oxide.
Post-foaming Agent
The post-foaming agent preferably comprises at least one hydrocarbon propellant selected from the group consisting of propane, n-pentane, isopentane, neopentane, n-butane, isobutane, and mixtures thereof. More preferably, the post-foaming agent comprises, and most preferably consists of, a mixture of isobutane and isopentane. Preferably, the weight ratio of isobutane:isopentane is about 0.70:2.25 (i.e., about 1:3). The post-foaming agent preferably is present in an amount of about 0.1 to about 10% by weight of the total post-foaming shaving gel composition, and more preferably about 3%. Most preferably, the isobutane used is A-31 propellant, sold under the names xe2x80x9cAEROPRES 31xe2x80x9d (Aeropres Corp.), xe2x80x9cAERON 31xe2x80x9d (Diversified Chemicals), xe2x80x9cA-31xe2x80x9d (Phillips Petroleum), xe2x80x9cMAIP-31 Propellantxe2x80x9d (Demert), or xe2x80x9cA-31xe2x80x9d (Technical Propellants).
Water
Water serves as a solvent for the surfactant system, and also aids in softening the hair which is to be removed from the skin during shaving, when the composition of this invention is formulated as a post-foaming shaving gel. Water is preferably present in an amount of at least about 60% by total weight of the post-foaming shaving gel composition, and most preferably in an amount of about 75% by total weight. The addition of too much water might soften the gel undesirably, while the use of too little water might make the gel too thick to manufacture easily. Preferably, deionized water is used, as the use of ionized water might have an adverse effect upon gel formation.
Optional Ingredients
The post-foaming shaving gel according to this invention may include one or more optional ingredients or adjuvants, including, for example, emollients, humectants, colorants, and fragrances, which will be discussed in turn below. A variety of such additional optional ingredients or adjuvants may be added, as long as they do not materially change the fundamental character of the post-foaming shaving gel composition.
a. Emollients
Emollients provide lipids to replenish those lost in shaving, for example, and also may soften the hair to be removed by the razor during shaving so as to make it easier to cut. Secondarily, some emollients also have some effect on gel strength. Examples of preferred emollients include glycol esters selected from the group consisting of propylene glycol monoisostearate, propylene glycol dipelargonate, propylene glycol oleate, propylene glycol myristate, and mixtures thereof, with propylene glycol monoisostearate being preferred.
Examples of especially preferred emollients include a distilled monoglyceride of sunflower oil which is sold under the trademark xe2x80x9cMyverol 18-92xe2x80x9d by Eastman Chemical Products, and lanolin alcohol (preferably xe2x80x9cSuper Hartolanxe2x80x9d lanolin alcohol, sold by Croda).
b. Humectants
Humectants optionally may be included, and serve to retain water, to prevent the gel from drying out, and to prevent the nozzle of the dispenser, in which the post-foaming shaving gel may be stored, from drying up and clogging. Examples of preferred humectants include polyhydric alcohols selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, glycerin, and sorbitol, with sorbitol being most preferred. Preferably, the sorbitol used in this invention is that which is referred to in the art as xe2x80x9csorbitol, 70% USPxe2x80x9d (USP refers to the U.S. Pharmacopeia reference handbook, which is incorporated herein in its entirety by reference), most preferably that which is sold by ADM Food Additives, Merck (under the name xe2x80x9cSorboxe2x80x9d), Roquette, or Pfizer Chemicals.
The glycerin used in this invention is preferably xe2x80x9cglycerin, USP, 99.5%xe2x80x9d, most preferably that which is sold by Dow Chemical, Inc., Emery Industries, Inc. (under the name xe2x80x9cSuperol 99.5%xe2x80x9d), and Procter and Gamble. Another preferred humectant is xe2x80x9cDL-panthenolxe2x80x9d, which is sold by Hoffman-Larches. Yet another preferred humectant is PEG/PPG 17/6 copolymer (17 moles ethylene oxide/6 moles propylene oxide), preferably that sold by PPG/Mazer Chemicals or Union Carbide, under the names xe2x80x9cMacol 450xe2x80x9d and xe2x80x9cUcon 75-H-450xe2x80x9d. Still another preferred humectant is phytantriol, preferably that sold by Roche.
c. Colorants
Colorants may also be added, optionally. Preferably, the colorants are those which have been approved for use in shaving gels, such as, for example, DandC dyes and FDandC dyes. Preferred examples of colorants include FDandC Blue #1, DandC Yellow #10, DandC Green #8, DandC Red #33, and FDandC Red #40, preferably those sold by H. Kohnstamm and Co., Warner Jenkinson, or Hilton Davis.
d. Fragrances
Fragrances optionally may be included for cosmetic effect, and preferably should be compatible with water-soluble soaps and detergents. Any known cosmetically acceptable fragrance may be employed. Fragrances preferably are present in a total amount less than or equal to 1% by total weight of the post-foaming shaving gel composition, and more preferably less than or equal to 0.5%.
e. Other Ingredients
As noted above, other ingredients or adjuvants optionally may be included in the post-foaming shaving gel according to this invention. Examples thereof include anti-oxidants such as BHT (preferably, xe2x80x9cSustane BHTxe2x80x9d sold by Quest), vitamin E, aloe vera powder (preferably xe2x80x9cCo Vera Dryxe2x80x9d sold by Costec, Inc., or that which is sold by Tri-K), allantoin (preferably that sold by Sutton Labs), or any other materials which provide desired properties.